Fatigue of textiles used in vascular surgery: Application to carotid endarterectomy.

Fatigue is a material-based phenomenon playing a significant role in the mechanical behavior of components and structures. Although fatigue has been well studied for traditional materials, such as metals, its underlying mechanisms are not thoroughly understood in novel applications such as the case of textiles used as patches to close the arteriotomy in carotid endarterectomy. The latter is a type of vascular surgery for the treatment of carotid artery disease in which after an arteriotomy and removal of atherosclerotic plaque closure is made with a patch sutured on the artery. Completion of the operation signals the initiation of complex mechanical and hemodynamic phenomena. Fatigue performance of the patch eventually determines the successful outcome of carotid endarterectomy. In this study, we evaluate with a two-fold approach the mechanics of patch angioplasty in carotid endarterectomy. First, an analytical model for the fatigue behavior of textiles is developed, considering the microstructure and geometry of the fabric. Then, the surgical procedure is simulated and a finite element analysis of the endarterectomized and patched carotid artery is employed. Stress fields are calculated, while deformation at the site of patch angioplasty indicates a potential cause for the formation of aneurismal degeneration after the surgery. Such analysis can provide a better understanding in the establishment of follow-up protocols.

A survey of the European Venous Forum on education and training in venous surgery and phlebology in Europe.

AIM: Venous training in Europe is lacking a formal curriculum among various specialties related to management of venous diseases. We conducted a survey in order to have a snapshot on the actual education and training level among physicians practicing currently venous surgery and phlebology in Europe. METHODS: From April 7, 2014 to June 11, 2014 a survey was carried out using the Survey Monkey system, including 11 main questions covering all the domains of training and education in venous surgery and phlebology. The questionnaire was sent to all physicians included in the current mailing list of the European Venous Forum (EVF) and the Mediterranean League of Angiology and Vascular Surgery. Two questions were particularly addressed to those physicians who had attended the EVF hands-on workshop (HOW) at least once. RESULTS: The response rate was 24% (97/400) and 51.5% of them were practicing in a hospital service. Most responders were vascular surgeons (67.7%), followed by angiologists (19.4%). Only half of the responders felt as being competent to manage the whole spectrum of venous diseases successfully after completion of their training, while a few were able to perform endovenous ablations and even less more advanced venous interventions. Formal training in Duplex ultrasound was undertaken only in 55.2%. The majority suggested that a venous training program should be a separate part of their specialty rotation and should be organized at a national or European level, or even by a specific scientific society. Over 95% of those physicians who already participated in the EVF HOW considered the knowledge they acquired there as useful for their practice. CONCLUSION: There is currently an important need for more specialized venous training for all physicians involved in the diagnosis and management of venous diseases. Therefore all local, national and international initiatives should be encouraged to improve education in this field.

Comparison of cognitive function after carotid artery stenting versus carotid endarterectomy.

The effect of carotid artery stenting (CAS) and carotid endarterectomy (CEA) on cognitive function is unclear. Both cognitive improvement and decline have been reported after CAS and CEA. We aimed to compare the changes in postprocedural cognitive function after CAS versus CEA. A systematic qualitative review of the literature was conducted according to the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement for studies evaluating the changes in cognitive function after CAS compared with CEA. Thirteen studies (403 CEAs; 368 CAS procedures) comparing the changes in cognitive function after CEA versus CAS were identified. Most studies did not show significant differences in overall cognitive function or only showed a difference in a single cognitive test between the two procedures. A definitive conclusion regarding the effect of CAS versus CEA on cognitive function was not possible owing to heterogeneity in definition, method, timing of assessment, and type of cognitive tests. For the same reasons, performing a meta-analysis was not feasible. The lack of standardization of specific cognitive tests and timing of assessment of cognitive function after CAS and CEA do not allow for definite conclusions to be drawn. Larger, adequately-powered and appropriately designed studies are required to accurately evaluate the effect of CAS versus CEA on postprocedural cognitive function.

Phlebosclerosis in lower extremities veins.

OBJECTIVES: To determine the prevalence, distribution and extent of phlebosclerosis in an outpatient population referred to vascular clinic. DESIGN: Prospective cohort study. PATIENTS AND METHODS: Seven hundred and forty consecutive patients, 302 (41%) men with a cohort median age of 49 (range, 18-84), were referred to the vascular clinic for detection of lower extremity acute or chronic venous disease. A total of 1000 limbs were assessed using duplex ultrasonography. Deep veins were not assessed. Characteristics of venous wall and lumen were studied. Phlebosclerosis was diagnosed based on the increased echogenicity and thickness or calcification of the venous wall. Patients with known trauma or any surgery in the lower extremities were excluded. Two control groups were used for comparison, one of consecutive patients undergoing vein mapping (n = 100) and the other of younger volunteers free of any vein disease (n = 25). RESULTS: Of the 1000 limbs (right: 458, left: 542) studied by duplex ultrasound, 21 limbs had intense brightness of the venous wall. Fifteen of them had also calcifications and 61 wall thickening. The prevalence of phlebosclerosis was significantly higher in the patient group when compared with control groups 1 (P = 0.019) and 2 (P = 0.011). The mean age of patients with phlebosclerosis was higher compared with the whole patient group (57 versus 49 years, P < 0.0001). Phlebosclerosis affected all superficial veins with greater prevalence in the small saphenous vein (SSV). The mean length of the phlebosclerotic lesion was 2 cm (range 1-7 cm). CONCLUSION: The prevalence of phlebosclerosis in the lower extremities appears to be low with no significant sex differences. Age and chronic venous disease are important factors for its development. It may be present in the absence of thrombosis or reflux. A greater prevalence of phlebosclerotic lesions was found in the SSV.

Computational phlebology: reviewing computer models of the venous system.

Relatively little attention has been paid to the venous system and valves from a cardiovascular engineering perspective up to now. Given the involvement of venous valve haemodynamics in the development of deep vein thrombosis this is an area that needs more detailed investigation and close collaboration between clinicians and cardiovascular engineers. The purpose of this review article is to provide an indication of the physiological conditions that need to be included in any computational model of the venous system, based on recommendations from clinicians, and to summarize published computational models of the venous system by trying to explore their limitations and application range. A MEDLINE search was carried out on the relevant literature from 1940 until today. Several models have been developed with a specific purpose in mind to coincide with the aim of each individual study. The model complexity and laws used in each model vary significantly. There are more simplistic computational models based on electric circuit analogies, termed as lumped parameter models, which can be used to provide boundary conditions to one-dimensional (1D) and three-dimensional (3D) domain models, followed by 1D continuous models based on analytical equations, which allow the description of pressure wave and can be non-linear in nature. Finally, there are the more advanced 3D models, which are based on the principles of haemodynamics, and consider the compliance of the venous system and the effect that venous valves have on the cardiovascular system. In conclusion, it appears that computer modelling of the venous system can contribute greatly to our understanding of venous physiology and allow us to evaluate the haemodynamic interactions that occur in the venous system under different physiological conditions.